doc/redo-ifchange.html

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  <title>redo-ifchange(1) Redux User Manual</title>
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<h1 class="title">redo-ifchange(1) Redux User Manual</h1>
<h2 class="author">Gyepi Sam</h2>
<h3 class="date">October 03, 2018</h3>
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<h1 id="name">NAME</h1>
<p>ifchange - Creates dependency on targets and ensure that targets are up to date.</p>
<h1 id="synopsis">SYNOPSIS</h1>
<p>redux ifchange [TARGET...]</p>
<h1 id="options">OPTIONS</h1>
<p>-? Show help</p>
<p>-h Show help</p>
<p>-help</p>
<pre><code>    Show help</code></pre>
<h1 id="notes">NOTES</h1>
<p>The ifchange command creates a dependency on the target files and ensures that the target files are up to date, calling the redo command, if necessary.</p>
<p>The current file will be invalidated if a target is rebuilt.</p>
<h1 id="description">DESCRIPTION</h1>
<p>This command can be invoked as <code>redux ifchange</code> or, through a symlink, as <code>redo-ifchange</code>.</p>
<p>The <code>redo-ifchange</code> command is used in a <code>.do</code> script.</p>
<p>When the <code>.do</code> script for a target A contains the line <code>redo-ifchange B</code>, this means that the target A depends on B and A should be rebuilt if B changes.</p>
<p>This command should be placed in a <code>.do</code> script and not run directly.</p>
<h1 id="details">DETAILS</h1>
<p>Conceptually, redo-ifchange performs three tasks.</p>
<p>First, it creates a prerequisite record between A and B so A can track changes to B. Second, it creates a dependency record between B and A so a change in B immediately invalidates A. Finally, if B is out of date, redo-ifchange ensures that B is made up to date.</p>
<p>B is considered out of date if it does not exist, is not in the database, is flagged as out of date, has been modified or any of its dependents are out of date. Obviously this process may recurse.</p>
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